CN116710545A - Method for producing silica microcapsules - Google Patents

Abstract

The present invention relates to: [1] A method for producing a silica microcapsule having a shell containing silica as a constituent and a core containing one or more organic compounds, the production method comprising the following steps: Step: In the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions, the emulsion is subjected to a sol-gel reaction to form silica microcapsules, wherein , the emulsion is obtained by emulsifying a water phase component containing a cationic surfactant and an oil phase component containing one or more organic compounds and a silicon dioxide source; [2] an aqueous dispersion, the water dispersion The body contains silica microcapsules, the silica microcapsules have a shell comprising silica as a constituent and a core comprising one or more organic compounds, and the sulfate ions, sulfite ions, and sulfonate ions in the aqueous dispersion The total content of acid ions is 10 to 500 ppm.

Description

Method for producing silica microcapsules

technical field

The invention relates to a method for producing silicon dioxide microcapsules and an aqueous dispersion of silicon dioxide microcapsules.

Background technique

Various microcapsules containing fragrances and bioactive substances have been developed and used in a wide range of business fields such as cosmetics, pharmaceuticals, general household products, and printing. For example, aminoplast resins such as melamine resins and polyurea/urethane resins are used as shells constituting microcapsules. However, discharge of microcapsules into the environment cannot be avoided, and in recent years, they have become a cause of concern for substances called microplastics. Therefore, it is desired to develop microcapsules with high environmental compatibility instead of aminoplast resins.

Among them, silica microcapsules (hereinafter also referred to as “silica capsules”) having a shell containing silica as a constituent component have attracted attention as a material from which environmental compatibility can be expected.

Silica capsules are generally obtained by forming silica on the surface of emulsified droplets by a sol-gel method. However, since the silica capsule itself is a very fine particle, the shell of the silica capsule is also very thin and brittle. Therefore, due to the disintegration of the shell, the internal components of the silica capsule may diffuse through the micropores present in the shell, whereby a part of the internal components are eluted to the external environment. Therefore, studies have been conducted on various methods of producing silica capsules using the sol-gel method.

For example, in Japanese Patent Application Laid-Open No. 2013-255915 (Patent Document 1), a method for producing microcapsules having a core substance containing active ingredients such as sunscreens, the method for producing microcapsules includes the following steps: An oily phase composed of an insoluble precursor and a core substance is emulsified in an aqueous phase composed of an aqueous solution having a predetermined pH to produce an oil-in-water emulsion, wherein the aqueous phase used in this process contains Cationic surfactant.

In Japanese Patent Application Laid-Open No. 2015-128762 (Patent Document 2), the object is to provide a method for producing microcapsules capable of retaining active ingredients such as fragrances, that is, organic compounds for a long time, and the following content is described: In the method for producing microcapsules comprising a core, a first shell enclosing the core, and a second shell enclosing the first shell, an organic compound and a tetraalkoxysilane are emulsified in an aqueous phase containing a surfactant The first-stage sol-gel reaction is carried out in the state of the organic phase, and then tetraalkoxysilane is added to maintain a lower pH than the first-stage sol-gel reaction, and the second-stage sol-gel reaction is performed. reaction.

Contents of the invention

The present invention provides a kind of manufacture method of silicon dioxide microcapsule, wherein,

The silica microcapsules have: a shell containing silica as a constituent; and a core containing one or more organic compounds inside the shell,

The method for producing silica microcapsules includes the following steps: in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions, supplying the emulsion to the sol-gel reaction to form silica microcapsules,

The emulsion is obtained by emulsifying a water phase component containing a cationic surfactant and an oil phase component containing one or more organic compounds and a silica source.

Detailed ways

It was confirmed that in the techniques of Patent Documents 1 and 2, depending on the included oil agents, the target silica capsules that suppress leakage of core components may not be obtained, and organic compounds such as fragrances may not be sufficiently retained at a high inclusion rate.

The present invention relates to a method for producing silica microcapsules and an aqueous dispersion containing silica microcapsules. The silica microcapsules of the present invention stably contain organic compounds such as active ingredients such as fragrances at a high inclusion rate.

The inventors of the present invention have found that by subjecting an emulsion containing sulfate ions, sulfite ions, or sulfonate ions in the system to the sol-gel reaction, it is possible to obtain an organic compound that stably contains active ingredients such as fragrances at a high inclusion rate. Compounds in silica microcapsules.

That is, the present invention relates to the following [1] and [2].

[1] A method for producing silica microcapsules, wherein the silica microcapsules have: a shell containing silica as a constituent; and a core containing one or more organic compounds inside the shell,

The above-mentioned method for producing silica microcapsules includes the step of subjecting the emulsion to a sol-gel reaction in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions. And the process of forming silica microcapsules,

The emulsion is obtained by emulsifying a water phase component containing a cationic surfactant and an oil phase component containing one or more organic compounds and a silica source.

[2] An aqueous dispersion containing silica microcapsules, the silica microcapsules having: a shell containing silica as a constituent; and one or more organic compounds contained in the shell. nuclear,

The total content of sulfate ions, sulfite ions, and sulfonate ions in the aqueous dispersion is not less than 10 ppm and not more than 500 ppm.

According to the present invention, it is possible to provide a method for producing silica microcapsules and an aqueous dispersion containing silica microcapsules, wherein the silica microcapsules of the present invention stably contain organic compounds such as active ingredients such as fragrances at a high inclusion rate. .

[Manufacturing method of silica microcapsules]

The method for producing silica microcapsules (silica capsules) of the present invention is to produce silica capsules having a shell containing silica as a constituent and a core containing one or more organic compounds inside the shell. The method comprises the following steps (hereinafter also referred to as "step I"): in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions, the emulsion is supplied to the sol - A step of forming silica microcapsules by a gel reaction, wherein the emulsion is formed by emulsifying a water phase component containing a cationic surfactant and an oil phase component containing one or more organic compounds and a silica source owned.

The "silicon dioxide source" in the present invention refers to a substance that can form a shell of a silica capsule, and examples thereof include substances that produce silanol compounds by hydrolysis, such as tetraalkoxysilane.

The "sol-gel reaction" in the present invention refers to a reaction in which a silica source forms silica, which is a constituent component of the shell, through a sol and a gel state through hydrolysis and polycondensation reactions. As the sol-gel reaction, for example, the following reaction can be mentioned: tetraalkoxysilane is hydrolyzed as a silica source, and the silanol compound generates a siloxane oligomer through a dehydration condensation reaction and a dealcohol condensation reaction, and further A reaction in which a dehydration condensation reaction is performed to produce silica.

According to the present invention, it is possible to provide a method for producing silica capsules in which an organic compound, which is an active ingredient such as a fragrance, is stably contained at a high inclusion rate, and an aqueous dispersion containing silica capsules. The reason for this is unclear, but it is considered as follows.

In the production method of the present invention, since a cationic surfactant is used as an emulsifier for the emulsion used in the sol-gel reaction, the surface of the emulsified droplet that becomes the mold of the silica capsule becomes positively charged. state. And it is considered that: in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions, the emulsion in which the emulsified droplets are formed is subjected to a sol-gel reaction, Thus, sulfate ions, sulfite ions, or sulfonate ions present in the system acquire a resonance structure through delocalization of electrons contained between at least two oxygen atoms and one sulfur atom, and therefore, these ions At least two oxygen atoms of the silica capsule are negatively charged, passing between the at least two negatively charged oxygen atoms and the positively charged nitrogen atoms of the cationic surfactant on the surface of the emulsified droplet of the mold of the silica capsule The electrostatic interaction of the cationic surfactant on the surface of the emulsified droplet becomes denser, and the charge density on the surface of the emulsified droplet becomes higher. In this state, the formation of the shell at the interface of the emulsified droplet is accelerated, forming Dense and firm shell. As a result, it is considered that the leakage of the core component can be suppressed, and a silica capsule stably encapsulating an organic compound at a high encapsulation rate can be provided.

＜Emulsion＞

The emulsion used in the production method of the present invention is obtained by emulsifying a water phase component containing a cationic surfactant and an oil phase component containing one or more organic compounds and a silica source.

〔Cationic surfactant〕

The aqueous phase component of the said emulsion contains a cationic surfactant.

As said cationic surfactant, an alkylamine salt, an alkyl quaternary ammonium salt, etc. are mentioned, for example. The number of carbon atoms in the alkyl group of the alkylamine salt and the alkyl quaternary ammonium salt is preferably 10 or more, more preferably 12 or more, further preferably 14 or more, and preferably 22 or less, more preferably 20 or less, and even more preferably under 18.

Examples of the alkylamine salt include alkylamine acetates such as laurylamine acetate and stearylamine acetate.

As said alkyl quaternary ammonium salt, an alkyl trimethyl ammonium salt, a dialkyl dimethyl ammonium salt, an alkyl benzyl dimethyl ammonium salt, etc. are mentioned.

The counter ion of the cationic group of the cationic surfactant is preferably a halide ion such as a chloride ion or a bromide ion, more preferably a chloride ion.

It is considered that when the counter ion of the cationic group of the above-mentioned cationic surfactant is a chloride ion, the reaction from the chloride ion to the sulfate ion and sulfurous acid derived from the compound (A) is effectively induced on the surface of the emulsified droplet. The exchange reaction of ions or sulfonic acid ions, the filling of the cationic surfactant on the surface of the emulsified droplet becomes tight, which increases the charge density on the surface of the emulsified droplet, accelerates the formation of the shell on the interface of the emulsified droplet, and can form a dense and solid shell. It is considered that as a result, the inclusion rate of the organic compound is increased, and stably included silica capsules can be obtained.

Examples of the above-mentioned alkyltrimethylammonium salts include alkyltrimethylchlorides such as lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, and stearyltrimethylammonium chloride. Ammonium chloride; alkyl trimethyl ammonium bromide such as lauryl trimethyl ammonium bromide, cetyl trimethyl ammonium bromide, stearyl trimethyl ammonium bromide, etc.

Examples of the dialkyldimethylammonium salts include: dialkyldimethylammonium chloride such as distearyldimethylammonium chloride; dialkyldimethylammonium chloride such as distearyldimethylammonium bromide; Dimethylammonium bromide, etc.

As said alkyl benzyl dimethyl ammonium salt, an alkyl benzyl dimethyl ammonium chloride, an alkyl benzyl dimethyl ammonium bromide, etc. are mentioned.

With regard to the above-mentioned cationic surfactants, one type may be used alone or two or more types may be used.

Among these substances, the above-mentioned cationic surfactant is preferably a quaternary ammonium salt, more preferably an alkyltrimethylammonium salt having an alkyl group having 10 to 22 carbon atoms, and further preferably an alkyltrimethylammonium salt having an alkyl group having 10 or more carbon atoms. Alkyltrimethylammonium halides of alkyl groups of 22 or less, more preferably alkyltrimethylammonium chlorides having alkyl groups of 10 to 22 carbon atoms, more preferably selected from lauryltrimethylammonium chloride At least one of ammonium chloride, stearyltrimethylammonium chloride, and cetyltrimethylammonium chloride, more preferably cetyltrimethylammonium chloride.

The amount of the cationic surfactant used in the production method of the present invention is preferably 0.1% by mass or more relative to the amount of the above-mentioned organic compound from the viewpoint of obtaining a stable emulsion and stably incorporating the organic compound at a high inclusion rate. More preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, still more preferably 0.7% by mass or less.

Here, the quantity of a cationic surfactant is the ratio when the quantity of the said organic compound is made into 100 mass %.

It is to be noted that the content of the cationic surfactant in the above-mentioned aqueous phase component is preferably less than 0.5% by mass from the viewpoint of obtaining a stable emulsion and effectively incorporating organic compounds.

〔organic compound〕

The oil phase component of the said emulsion contains 1 or more types of organic compounds.

The above-mentioned organic compound is preferably selected from fragrances, fragrance precursors, oil agents (moisturizers), antioxidants, antibacterial agents, fertilizers, fibers, skin, and hair surface modifiers, cooling agents, dyes, pigments, silicones, etc. One or more of ketones, solvents, and oil-soluble polymers, more preferably selected from fragrances, fragrance precursors, oils (moisturizers), antioxidants, antibacterial agents, fertilizers, surface modifiers, and solvents One or more, more preferably one or more selected from fragrances, fragrance precursors, humectants, antioxidants, and solvents, still more preferably one or more selected from fragrances, fragrance precursors, and oil agents, More preferably, it is one or more types selected from fragrances and fragrance precursors.

With regard to the above-mentioned organic compounds, one type may be used alone or two or more types may be used.

As said fragrance precursor, the compound which reacts with water and releases a fragrance component, the compound which reacts with light and releases a fragrance component, etc. are mentioned.

Examples of compounds that react with water to release fragrance components include silicate compounds having an alkoxy component derived from fragrance alcohol, fatty acid ester compounds having an alkoxy component derived from fragrance alcohol, fatty acid ester compounds derived from An acetal compound or hemiacetal compound obtained by reacting a carbonyl component of a fragrance aldehyde or a fragrance ketone with an alcohol compound, a Schiff base compound obtained by reacting a carbonyl component derived from a fragrance aldehyde or a fragrance ketone and a primary amine compound, A hemiamine acetal compound or hydrazone compound obtained by reacting a carbonyl component derived from a fragrance aldehyde or a fragrance ketone with a hydrazine compound.

Examples of compounds that release fragrance components by reacting with light include: 2-nitrobenzyl ether compounds having an alkoxy component derived from fragrance alcohols, α-ketones having a carbonyl component derived from fragrance aldehydes or fragrance ketones An ester compound, a coumarate compound having an alkoxy component derived from a perfume alcohol. These pro-fragrances can be used, for example, as polymers such as reaction products of some carboxyl groups of polyacrylic acid and perfume alcohols.

From the viewpoint of obtaining a stable emulsion and stably incorporating the organic compound at a high inclusion rate, the organic compound preferably has appropriate hydrophobicity.

As an index showing the hydrophilicity or hydrophobicity of the above-mentioned organic compound, the calculated value of the common logarithm LogP of the partition coefficient P (n-octanol/water) between n-octanol and water, that is, the cLogP value can be used. The cLogP value is the LogP (cLogP) calculated by the method described in A. LeoComprehensive Medicinal Chemistry, Vol. 4 C. Hansch, P.G. Sammens, J.B Taylor and C.A. Ramsden, Eds., P. 295, Pergamon Press, 1990, is the value calculated by the program CLOGP v4.01.

When the above-mentioned organic compound is composed of a plurality of constituent components, the cLogP value of the organic compound can be obtained by multiplying the cLogP value of each constituent component by the volume ratio of each constituent component, and calculating the sum thereof.

The cLogP value of the organic compound is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and preferably 30 or less, more preferably 20 or less, and still more preferably 10 or less.

〔Silica source〕

The oil phase component of the above-mentioned emulsion contains a silica source.

From the viewpoint of forming a dense and firm shell and stably encapsulating organic compounds with a high encapsulation rate, the silica source preferably contains tetraalkoxysilane as a main component, and more preferably has a carbon number of 1 to 4. The alkoxy tetraalkoxysilane, more preferably one or more selected from tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane, more preferably selected from tetramethoxysilane One or more of tetraethoxysilane and tetraethoxysilane, more preferably tetraethoxysilane.

When the above-mentioned silica source contains tetraalkoxysilane, it may also contain trialkoxysilanes such as triethoxysilane and trimethoxysilane, but the tetraalkoxysilane in the above-mentioned silica source The content is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, and preferably 100% by mass or less.

From the viewpoint of forming a shell surrounding oil-phase emulsion droplets containing organic compounds, the amount of the silica source used in the production method of the present invention is preferably 10% by mass or more relative to the amount of the above-mentioned organic compound, more preferably Preferably it is 15% by mass or more, more preferably 20% by mass or more, and from the viewpoint of suppressing the residue of the silica source inside the oil phase droplets and effectively performing conversion of the silica source to the shell, preferably It is 100 mass % or less, more preferably 70 mass % or less, still more preferably 50 mass % or less, still more preferably 30 mass % or less.

Here, the quantity of a silica source is the ratio when the quantity of the said organic compound is made into 100 mass %.

From the viewpoint of production efficiency, the amount of the oil phase component in the total amount of the emulsion is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, still more preferably 20% by mass % or more, and from the viewpoint of obtaining a stable emulsion, it is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, still more preferably 35% by mass or less, and even more preferably Preferably it is 30 mass % or less.

(preparation of emulsion)

In the present invention, the emulsion is preferably prepared by a method including the following steps 1 to 3.

Step 1: A step of preparing an aqueous phase component containing a cationic surfactant.

Step 2: a step of preparing an oil phase component by mixing one or more organic compounds and a silica source.

Step 3: a step of mixing and emulsifying the water phase component obtained in step 1 and the oil phase component obtained in step 2 to obtain an emulsion.

From the viewpoint of productivity, the stirring device used for mixing the organic compound and the silica source in step 2 is preferably the same as the stirring device used for mixing and emulsifying the water phase component and oil phase component in step 3.

The stirring device used in Step 2 and Step 3 is not particularly limited, and a homogenizer having a strong shearing force, a high-pressure disperser, an ultrasonic disperser, and the like can be used. In addition, homomixers, "Disper" (trade name, manufactured by Primix Co., Ltd.), "CLEARMIX" (trade name, manufactured by M-Technique Co., Ltd.), "CAVITRON" (trade name, manufactured by Pacific Kiko Co., Ltd.) can also be used. Society system), etc.

From the viewpoint of reducing the specific surface area of silica capsules relative to the external environment and increasing the inclusion rate of organic compounds, the median diameter _D50 of the emulsion droplets of the above-mentioned emulsion is preferably 0.1 μm or more, more preferably 0.2 μm or more. μm or more, more preferably 0.3 μm or more, still more preferably 0.5 μm or more, and from the viewpoint of improving the physical strength of the silica capsule and stably including an organic compound with a high inclusion rate, preferably 50 μm or less, It is more preferably 30 μm or less, still more preferably 10 μm or less, still more preferably 5 μm or less, still more preferably 3 μm or less, still more preferably 2 μm or less.

The above-mentioned median diameter _D50 can be measured by the method described in the Examples.

[Compound (A)]

In the production method of the present invention, the emulsion is subjected to the sol-gel reaction described later in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions.

From the viewpoint of forming a dense and firm shell and stably including organic compounds with a high inclusion rate, the above-mentioned sulfur-containing ions are preferably selected from sulfate ions, sulfurous acid ions, aromatic sulfonate ions, and aliphatic sulfonate ions. One or more of them, more preferably one or more selected from sulfate ions, sulfite ions, and p-toluenesulfonate anions, more preferably one or more selected from sulfate ions and sulfite ions, and even more Sulfate ion is preferred.

In step I, as a method of carrying out the sol-gel reaction in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfurous acid ions, and sulfonate ions, it is preferable to add Sol-gel reaction is performed after one or more compounds (A) selected from sulfuric acid, sulfurous acid, sulfonic acid compounds, and salts thereof. Thus, there are sulfate ions, sulfite ions, or anions of sulfonate ions in the system of the emulsion, the filling of the cationic surfactant on the surface of the emulsified droplet becomes tight, and the charge density on the surface of the emulsified droplet becomes high. In this state, the formation of the shell on the emulsified droplet interface is accelerated to form a dense and strong shell capable of suppressing leakage of the core component. As a result, a silica capsule stably encapsulating an organic compound at a high encapsulation rate is obtained.

In the production method of the present invention, other anion species other than sulfate ions, sulfite ions, and sulfonate ions may coexist in the emulsion system within the range that does not inhibit the effects of the present invention.

The compound (A) is at least one selected from sulfuric acid, sulfurous acid, sulfonic acid compounds, and salts thereof.

The sulfonic acid compound is an organic compound having one or more sulfonic acid groups in the molecule, specifically, aromatic sulfonic acid compounds such as p-toluenesulfonic acid and benzenesulfonic acid; aliphatic sulfonic acid compounds such as methanesulfonic acid wait.

The salt of compound (A) is preferably an inorganic salt. For example, salts of alkali metals such as sodium and potassium; salts of alkaline earth metals such as calcium and magnesium, and the like are mentioned.

The compound (A) is preferably one or more selected from sulfuric acid, sulfurous acid, sulfonic acid compounds, and inorganic salts thereof, from the viewpoint of forming a dense and firm shell and stably encapsulating the organic compound at a high encapsulation rate. , more preferably one or more selected from sulfuric acid, sulfurous acid, p-toluenesulfonic acid, and their inorganic salts, more preferably one or more selected from sulfuric acid, sulfurous acid, and their inorganic salts, and even more Preferably at least one selected from sulfuric acid and its inorganic salts, more preferably at least one selected from sulfuric acid, sodium sulfate, and magnesium sulfate, still more preferably at least one selected from sulfuric acid and sodium sulfate , It is more preferable to contain sulfuric acid or its salt.

In addition, it is considered that when the compound (A) is one or more selected from sulfuric acid, sulfurous acid, and sulfonic acid compounds, it can also function as an acid catalyst for the sol-gel reaction and make the emulsified droplet interface The formation of the upper shell is accelerated, a dense and firm shell capable of suppressing leakage of the core component is formed, and a silica capsule stably encapsulating an organic compound at a high encapsulation rate is obtained.

The compound (A) can be used individually by 1 type or in combination of 2 or more types.

Regarding the amount of the compound (A) used in the production method of the present invention, from the viewpoint of forming a dense and firm shell and stably including the organic compound at a high inclusion rate, the total molar amount of sulfur-containing ions relative to the cation The molar ratio of the molar amount of the counter ion of the cationic group of the active agent [sulfur-containing ion/counter ion of the cationic group] is preferably 0.01 or more, more preferably 0.03 or more, and even more preferably 0.05 or more, Furthermore, it is preferably 2 or less, more preferably 1.5 or less, still more preferably 1.0 or less, still more preferably 0.7 or less, still more preferably 0.5 or less, still more preferably 0.3 or less, still more preferably 0.2 or less, still more preferably 0.1 or less, more preferably 0.07 or less.

It should be noted that when calculating the above-mentioned molar ratio [sulfur-containing ion/counter ion of cationic group], in the case where there are two or more kinds of sulfur-containing ions, the molar amount of sulfur-containing ions is the total mole of them In addition, when there are two or more kinds of counter ions of the cationic group, the molar amount of the counter ion of the cationic group is their total molar weight.

In addition, when the compound (A) has a function as an acid catalyst, the compound used in the production method of the present invention ( The amount of A) is preferably added so as to be within the range of the initial pH of the sol-gel reaction described later.

In the present invention, the molar ratio of the total molar amount of sulfur-containing ions to the molar amount of halide ions in the system is [ Sulfur-containing ion/halide ion] is preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.03 or more, and is preferably 0.3 or less, more preferably 0.15 or less, still more preferably 0.1 or less, and still more preferably 0.07 or less.

The halide ions here are chloride ions, bromide ions, iodide ions and the like.

It should be noted that, when calculating the above-mentioned molar ratio [sulfur-containing ion/halide ion], when there are two or more kinds of sulfur-containing ions, the molar amount of the sulfur-containing ions is their total molar amount. In addition, When two or more kinds of halide ions exist, the molar amount of the halide ions is their total molar amount.

(sol-gel reaction)

In the present invention, in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions, the emulsion is subjected to a sol-gel reaction to form a A shell constituting the ingredients and silica capsules containing the core of the above-mentioned organic compound inside the shell, and an aqueous dispersion containing the silica capsules are obtained.

The above-mentioned sol-gel reaction is preferably carried out under acidic conditions.

The initial pH of the above-mentioned sol-gel reaction is preferably 3.0 or more from the viewpoint of maintaining the balance between the hydrolysis reaction and the condensation reaction of the shell source, suppressing the generation of a highly hydrophilic sol, and promoting the progress of encapsulation. , more preferably 3.3 or more, more preferably 3.5 or more, and from the viewpoint of suppressing the formation of shells and the aggregation of emulsified droplets at the same time, and obtaining silica capsules with dense and firm shells, it is preferably 4.5 or less , more preferably 4.3 or less, even more preferably 4.1 or less.

In order to adjust the initial pH of the above-mentioned sol-gel reaction to a desired range, it is preferable that any acidic or alkaline A pH regulator is added to the emulsion.

When the pH of the emulsion is below a desired value, it is preferable to adjust using a basic pH adjuster.

When the pH of the emulsion is more than a desired value, it is preferable to adjust it using an acidic pH adjuster.

The above-mentioned compound (A) can also be added as a pH adjuster, but an acidic pH adjuster other than the compound (A) can also be used. Examples of the pH adjuster include inorganic acids such as hydrochloric acid and nitric acid; organic acids such as citric acid; and liquids in which a cation exchange resin or the like is added to water or ethanol.

Examples of alkaline pH regulators include: hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide; bicarbonates of alkali metals such as sodium bicarbonate; ammonia; ammonium hydroxide; diethanolamine, triethanolamine, Organic amines such as trishydroxymethylaminomethane, etc. Among them, one or more kinds selected from sodium hydroxide and ammonium hydroxide are preferable.

About the said pH adjuster, 1 type can be used individually or 2 or more types can be used.

In the present invention, it is preferable to use the compound (A) as an acidic pH adjuster from the viewpoint of ease of production. In this case, the compound (A) is more preferably at least one selected from sulfuric acid, sulfurous acid, and p-toluenesulfonic acid, further preferably at least one selected from sulfuric acid and sulfurous acid, and even more preferably sulfuric acid. .

It should be noted that, in the present invention, even when inorganic salts such as hydrochloric acid and nitric acid other than compound (A), organic acids such as citric acid, etc. are used as an acidic pH adjuster, by adding sodium sulfate , magnesium sulfate salt, etc. as the compound (A), and the same suitable conditions for the sol-gel reaction as the case where a substance having a function as a pH adjuster such as sulfuric acid is used as the compound (A).

Regarding the reaction temperature of the above-mentioned sol-gel reaction, as long as it is above the melting point and below the boiling point of the water contained as the dispersion medium, any value can be selected, and from the point of controlling the hydrolysis reaction and condensation reaction in the sol-gel reaction From the viewpoint of forming a dense and firm shell and stably incorporating organic compounds with a high inclusion ratio, it is preferably 5°C or higher, more preferably 10°C or higher, still more preferably 15°C or higher, and preferably 60°C or less, more preferably 50°C or less, even more preferably adjusted to 40°C or less.

In the present invention, the silica capsules obtained in the above-mentioned step I are obtained in the form of an aqueous dispersion containing silica capsules dispersed in water. The silica capsules obtained in this step I are silica capsules having a shell with a single-shell structure.

In addition, in the present invention, the following step (hereinafter, also referred to as "step II") may be included: further adding a silica source to the aqueous dispersion containing silica capsules obtained in the above step I to perform sol - A step of forming a silica capsule having a shell that further encloses the silica capsule by a gel reaction. It is considered that through step II, a shell is further formed on the silica capsule having a single-shell structure formed in step I, and the silica capsule obtained in step II becomes silica having a single-shell structure in which the thickness of the shell is increased. capsule. In addition, it is considered that the silica capsule having a double-shell structure is obtained through the step II, wherein the shell formed in the step I is an inner shell, and the shell formed in the step II is an outer shell.

The temperature of the sol-gel reaction in step II may be the same as that in step I.

The amount of the silica source in step II is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more relative to the amount of the above-mentioned organic compound. From the viewpoint of remaining in the phase liquid droplet and efficiently converting the silica source to the shell, it is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

From the viewpoint of reducing the number of production steps and efficiently producing silica capsules stably containing organic compounds at a high inclusion rate, the production method of the present invention preferably forms silica capsules only through step I.

In addition, in the production method of the present invention, it is preferable to form silica capsules by performing Step I and Step II from the viewpoint of improving the physical strength of silica capsules and stably incorporating organic compounds at a high inclusion ratio.

[Aqueous dispersion containing silica microcapsules]

The silica microcapsules (silica capsules) of the present invention have a shell containing silica as a constituent and a core containing one or more organic compounds inside the shell, and the silica microcapsules contain obtained in the form of an aqueous dispersion of silica capsules in water.

In the present invention, depending on the application of the silica capsule, it can be used directly as an aqueous dispersion, but depending on the application of the silica capsule, it can also be used after separating the silica capsule from the aqueous dispersion. As the separation method, a filtration method, a centrifugation method, and the like can be employed.

From the viewpoint of stably including organic compounds at a high inclusion rate, the total content of sulfate ions, sulfurous acid ions, and sulfonate ions in the aqueous dispersion containing silica microcapsules of the present invention (total of sulfur-containing ions) content) is preferably 10 ppm or more, more preferably 13 ppm or more, further preferably 15 ppm or more, and preferably 500 ppm or less, more preferably 450 ppm or less, further preferably 400 ppm or less, further preferably 200 ppm or less, still more preferably 100 ppm or less , more preferably 70 ppm or less, still more preferably 50 ppm or less, still more preferably 30 ppm or less.

The total content of sulfur-containing ions in the aqueous dispersion of silica microcapsules can be measured by quantifying each component using ion chromatography. Moreover, calculation can also be performed from the compounding quantity of each component.

The average thickness of the shell of the silica capsule of the present invention is preferably 5 nm or more, more preferably 10 nm or more, and preferably 100 nm or less, more preferably 70 nm or less, from the viewpoint of stably encapsulating the organic compound at a high encapsulation rate. , more preferably 50 nm or less, still more preferably 30 nm or less, still more preferably 20 nm or less.

The average thickness of the above shell can be measured by transmission electron microscope (TEM) observation. Specifically, the thickness of the shell was actually measured on a photograph under observation with a transmission electron microscope. Change the field of view to do this. The distribution of the average thickness of the shell was obtained from the obtained data. The standard of the magnification of the transmission electron microscope is 10,000 times to 100,000 times, but it is appropriately adjusted according to the size of the silica capsule. Here, as a transmission electron microscope (TEM), for example, a trade name "JEM-2100" (manufactured by JEOL Ltd.) can be used.

From the viewpoint of improving the dispersion stability of silica capsules and stably including organic compounds with a high inclusion rate, the median particle diameter _D50 of the silica capsules of the present invention is preferably 0.1 μm or more, more preferably 0.5 μm or more. μm or more, more preferably 1 μm or more, and from the viewpoint of improving the physical strength of silica capsules and stably including organic compounds with a high inclusion rate, it is preferably 50 μm or less, more preferably 30 μm or less, even more preferably 10 μm or less, more preferably 5 μm or less, still more preferably 3 μm or less.

The median diameter _D50 of the above-mentioned silica capsules can be measured by the method described in Examples.

The silica capsules and aqueous dispersions containing silica capsules of the present invention can be used in various applications, for example, they can be applied to emulsions, lotions, lotions, lotions, creams, gel preparations, and hair treatments. Fragrance and cosmetics such as quasi-drugs, detergents, softeners, fiber treatment agents such as anti-wrinkle sprays, hygiene products such as paper diapers, fragrances, etc.

Regarding the above-mentioned embodiments, the present invention also discloses the following method for producing silica microcapsules and an aqueous dispersion containing silica microcapsules.

<1> A method for producing silica microcapsules, wherein,

The silica microcapsules have: a shell containing silica as a constituent; and a core containing one or more organic compounds inside the shell,

The method for producing silica microcapsules includes the following steps: in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions, supplying the emulsion to the sol-gel The step of reacting to form silica microcapsules, wherein the emulsion is obtained by emulsifying a water phase component containing a cationic surfactant and an oil phase component containing one or more organic compounds and a silica source.

<2> The method for producing silica microcapsules according to the above <1>, wherein the sulfur-containing ion is preferably selected from sulfate ions, sulfite ions, aromatic sulfonate ions, and aliphatic sulfonate ions. One or more, more preferably one or more selected from sulfate ions, sulfite ions, and p-toluenesulfonate anions, more preferably one or more selected from sulfate ions and sulfite ions, even more preferably for sulfate ions.

<3> The method for producing silica microcapsules according to the above <1> or <2>, wherein in the step of forming the silica microcapsules, adding sulfuric acid, One or more compounds (A) among sulfurous acid, sulfonic acid compounds, and salts thereof are subjected to the sol-gel reaction.

<4> The method for producing silica microcapsules according to the above <3>, wherein the compound (A) is preferably at least one selected from sulfuric acid, sulfurous acid, sulfonic acid compounds, and inorganic salts thereof , more preferably one or more selected from sulfuric acid, sulfurous acid, p-toluenesulfonic acid, and their inorganic salts, more preferably one or more selected from sulfuric acid, sulfurous acid, and their inorganic salts, and even more Preferably at least one selected from sulfuric acid and its inorganic salts, more preferably at least one selected from sulfuric acid, sodium sulfate, and magnesium sulfate, still more preferably at least one selected from sulfuric acid and sodium sulfate , It is more preferable to contain sulfuric acid or its salt.

<5> The method for producing silica microcapsules according to the above <3> or <4>, wherein the amount of the compound (A) is the total molar amount of sulfur-containing ions relative to the amount of the cationic surfactant The molar ratio of the molar amount of the counter ion of the cationic group [sulfur-containing ion/the counter ion of the cationic group] is preferably 0.01 or more, more preferably 0.03 or more, still more preferably 0.05 or more, and preferably 2 or less, more preferably 1.5 or less, even more preferably 1.0 or less, still more preferably 0.7 or less, still more preferably 0.5 or less, still more preferably 0.3 or less, still more preferably 0.2 or less, still more preferably 0.1 or less, and even more preferably 0.1 or less. More preferably, it is 0.07 or less.

<6> The method for producing silica microcapsules according to any one of <1> to <5> above, wherein from the viewpoint of forming a dense and firm shell and stably encapsulating the organic compound at a high encapsulation rate From this point of view, the molar ratio of the total molar amount of sulfur-containing ions to the molar amount of halide ions in the system [sulfur-containing ions/halide ions] is preferably 0.01 or more, more preferably 0.02 or more, and even more preferably 0.03 or more, Furthermore, it is preferably 0.3 or less, more preferably 0.15 or less, still more preferably 0.1 or less, still more preferably 0.07 or less.

<7> The method for producing silica microcapsules according to any one of <1> to <6> above, wherein the silica source contains tetraalkoxysilane as a main component.

<8> The method for producing silica microcapsules according to any one of the above <7>, wherein the content of tetraalkoxysilane in the silica source is preferably 80% by mass or more, more preferably 85% by mass or more, more preferably 90% by mass or more, and preferably 100% by mass or less.

<9> The method for producing silica microcapsules according to any one of <1> to <8> above, wherein the amount of the silica source is preferably 10% by mass or more relative to the amount of the organic compound , more preferably 15% by mass or more, more preferably 20% by mass or more, and preferably 100% by mass or less, more preferably 70% by mass or less, further preferably 50% by mass or less, still more preferably 30% by mass or less .

<10> The method for producing silica microcapsules according to any one of <1> to <9> above, wherein the cationic surfactant is preferably a quaternary ammonium salt, more preferably has a carbon number of An alkyltrimethylammonium salt of an alkyl group of 10 to 22, more preferably an alkyltrimethylammonium halide having an alkyl group with a carbon number of 10 to 22, more preferably an alkyltrimethylammonium halide having an alkyl group with a carbon number of 10 The alkyl trimethyl ammonium chloride of the above 22 or less alkyl groups is more preferably selected from lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, and hexadecyl trimethyl ammonium chloride One or more kinds of ammonium chloride, more preferably cetyltrimethylammonium chloride.

<11> The method for producing silica microcapsules according to any one of <1> to <10>, wherein the amount of the cationic surfactant is preferably 0.1% by mass relative to the amount of the organic compound Above, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, still more preferably 0.7% by mass the following.

<12> The method for producing silica microcapsules according to any one of <1> to <11> above, wherein the median diameter _D50 of the emulsified droplets of the above-mentioned emulsion is preferably 0.1 μm or more, More preferably 0.2 μm or more, still more preferably 0.3 μm or more, still more preferably 0.5 μm or more, and preferably 50 μm or less, more preferably 30 μm or less, still more preferably 10 μm or less, still more preferably 5 μm or less, still more preferably It is preferably 3 μm or less, more preferably 2 μm or less.

<13> The method for producing silica microcapsules according to any one of <1> to <12> above, wherein the stirring device used for emulsification of the water phase component and the oil phase component is a homogenizer , high pressure disperser, or ultrasonic disperser.

<14> The method for producing silica microcapsules according to any one of <1> to <13> above, wherein the initial pH of the sol-gel reaction is preferably 3.0 or higher, more preferably 3.3 or higher, More preferably, it is 3.5 or more, and it is preferably 4.5 or less, more preferably 4.3 or less, and still more preferably 4.1 or less.

<15> The method for producing silica microcapsules according to any one of <1> to <14> above, wherein the reaction temperature of the sol-gel reaction is preferably 5°C or higher, more preferably 10°C Above, more preferably 15°C or higher, and preferably 60°C or lower, more preferably 50°C or lower, even more preferably 40°C or lower.

<16> The method for producing silica microcapsules according to any one of <1> to <15> above, wherein the cLogP value of the organic compound is preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and preferably 30 or less, more preferably 20 or less, still more preferably 10 or less.

<17> The method for producing silica microcapsules according to any one of <1> to <16> above, wherein the organic compound is preferably selected from the group consisting of fragrances, fragrance precursors, oils (moisturizers), One or more of antioxidants, antibacterial agents, fertilizers, surface modifiers for fibers, skin, and hair, cooling agents, dyes, pigments, silicones, solvents, and oil-soluble polymers, more preferably selected from One or more of fragrances, fragrance precursors, oil agents (moisturizers), antioxidants, antibacterial agents, fertilizers, surface modifiers, and solvents, more preferably selected from fragrances, fragrance precursors, humectants, and antioxidants , and one or more solvents, more preferably one or more selected from fragrances, fragrance precursors, and oils, and still more preferably one or more selected from fragrances and fragrance precursors.

<18> The method for producing silica microcapsules according to any one of <1> to <17> above, wherein the silica microcapsules have a median diameter _D50 of preferably 0.1 μm or more, more preferably It is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 50 μm or less, more preferably 30 μm or less, still more preferably 10 μm or less, still more preferably 5 μm or less, still more preferably 3 μm or less.

<19> A method for producing silica microcapsules, wherein,

The silica microcapsules have: a shell containing silica as a constituent; and a core containing one or more organic compounds inside the shell,

The above-mentioned method for producing silica microcapsules includes the step of subjecting the emulsion to a sol-gel reaction in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions. And the process of forming silica microcapsules,

The above emulsion is obtained by emulsifying a water phase component and an oil phase component, the above water phase component contains a quaternary ammonium salt as a cationic surfactant, and the above oil phase component contains one or more organic compounds and tetraalkoxy Silane as the main component of the silica source,

The said organic compound is 1 or more types chosen from a fragrance and a fragrance precursor.

<20> The method for producing silica microcapsules according to the above <19>, wherein in the step of forming the silica microcapsules, adding a compound selected from sulfuric acid, sulfurous acid, and sulfonic acid to the emulsion One or more compounds (A) among the compounds and their salts are subjected to the sol-gel reaction.

<21> The method for producing silica microcapsules according to the above <20>, wherein the amount of the compound (A) is the total molar amount of sulfur-containing ions relative to the cationic group of the cationic surfactant The molar ratio of the molar amount of the counter ion [sulfur-containing ion/the counter ion of the cationic group] is preferably 0.01 or more, more preferably 0.03 or more, further preferably 0.05 or more, and is preferably 2 or less, more preferably 1.5 or less, more preferably 1.0 or less, still more preferably 0.7 or less, still more preferably 0.5 or less, still more preferably 0.3 or less, still more preferably 0.2 or less, still more preferably 0.1 or less, still more preferably 0.07 the following.

<22> The method for producing silica microcapsules according to any one of <19> to <21> above, wherein the cLogP value of the organic compound is preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and preferably 30 or less, more preferably 20 or less, still more preferably 10 or less.

<23> The method for producing silica microcapsules according to any one of <19> to <22> above, wherein the median diameter _D50 of the emulsified droplets of the emulsion is preferably 0.1 μm or more, More preferably 0.2 μm or more, still more preferably 0.3 μm or more, still more preferably 0.5 μm or more, and preferably 50 μm or less, more preferably 30 μm or less, still more preferably 10 μm or less, still more preferably 5 μm or less, still more preferably It is preferably 3 μm or less, more preferably 2 μm or less.

<24> The method for producing silica microcapsules according to any one of <19> to <23> above, wherein the initial pH of the sol-gel reaction is preferably 3.0 or higher, more preferably 3.3 or higher, More preferably, it is 3.5 or more, and it is preferably 4.5 or less, more preferably 4.3 or less, and still more preferably 4.1 or less.

<25> An aqueous dispersion, wherein,

containing silica microcapsules having a shell containing silica as a constituent and a core containing one or more organic compounds inside the shell,

The total content of sulfate ions, sulfite ions, and sulfonate ions in the aqueous dispersion containing silica microcapsules (total content of sulfur-containing ions) is preferably 10 ppm or more, more preferably 13 ppm or more, and even more preferably 15 ppm Above, and, preferably 500ppm or less, more preferably 450ppm or less, still more preferably 400ppm or less, still more preferably 200ppm or less, still more preferably 100ppm or less, still more preferably 70ppm or less, still more preferably 50ppm or less, still more preferably Preferably it is 30 ppm or less. More than 10ppm and less than 500ppm.

[Example]

Various measurements used in Examples and Comparative Examples were performed by the following methods.

〔median particle diameter _D50 〕

For the median diameter D ₅₀ of the emulsified liquid droplets and the median diameter D ₅₀ of the silica capsules, a laser diffraction/scattering particle size distribution measuring device "LA-960" (trade name, Horiba Manufacturing Co., Ltd. system) measurement. In the measurement, a flow cell was used, water was used as a medium, and the refractive index was set to 1.45-0i. An emulsion or an aqueous dispersion containing silica capsules was added to a flow cell, and the transmittance was measured at a concentration near 90%, and the median particle diameter D ₅₀ was obtained on a volume basis.

＜Model Spice A＞

As the organic compound contained in the silica capsule, model fragrance A (volume average cLogP value: 4.3) having the composition shown in Table 1 was used. It should be noted that, regarding the volume average cLogP value of the above-mentioned model fragrance, the cLogP values of all the components of the fragrance ingredients contained in the model fragrance are respectively multiplied by the volume ratio of each component in the model fragrance, and their ratios are obtained. and calculated.

[Table 1]

Table 1: Model Spice A

Fragrance ingredient name Content (mass%) cLogP Linalool twenty two 3.3 Linalyl acetate 16 4.4 Tetrahydrolinalool 16 3.6 other 46

Example 1

(Process I)

0.30 g of QUARTAMIN 60W (trade name, Kao Co., Ltd.; cetyltrimethylammonium chloride (in the following Table 2, described as "CTAC")) and active ingredient 30 were diluted with 74.70 g of ion exchanged water Mass %), prepare the water phase composition. The oil phase component prepared by mixing 20 g of model perfume A and 5 g of tetraethoxysilane (hereinafter referred to as "TEOS") was added to the water phase component, and a homomixer ( Hsiang Tai Co., Ltd., model: HM-310) emulsified the mixed solution to obtain an emulsion (1). The median diameter D ₅₀ of the emulsified liquid droplets at this time was 1.1 μm.

Next, 0.16 g of 1% by mass sulfuric acid aqueous solution was added to the obtained emulsion (1) to obtain an emulsion (1') whose pH was adjusted to 3.8, and the emulsion (1') was transferred to a separator equipped with a stirring blade. In a type flask, the liquid temperature was kept at 30° C. while stirring at 200 rpm for 24 hours to obtain water containing silica capsules (the silica capsules had a core composed of model flavor A and a shell composed of silica). Dispersion (I). The obtained silica capsules had a median particle diameter D ₅₀ of 2.1 μm.

Example 2

(Process I)

It carried out similarly to Example 1, and obtained the emulsion (1).

Next, 0.29 g of a 1% by mass sulfurous acid aqueous solution was added to the obtained emulsion (1) to obtain an emulsion (2') whose pH was adjusted to 3.8, and the emulsion (2') was transferred to an In the separate flask, the liquid temperature was kept at 30° C. while stirring at 200 rpm for 24 hours to obtain a silica capsule containing a silica capsule (the silica capsule had a core composed of model flavor A and a shell composed of silica). Aqueous Dispersion (II). The median particle size _D50 of the silica capsules was 2.2 μm.

Example 3

(Process I)

It carried out similarly to Example 1, and obtained the emulsion (1).

Next, 0.41 g of a 1% by mass aqueous solution of p-toluenesulfonic acid was added to the obtained emulsion (1) to obtain an emulsion (3') whose pH was adjusted to 3.7. In the separable flask with blades, keep the liquid temperature at 30°C while stirring at 200rpm for 24 hours to obtain capsules containing silica (the silica capsules have a core made of model flavor A and a shell made of silica). ) in aqueous dispersion (III). The median particle size _D50 of the silica capsules is 2.1 μm.

Example 4

(Process I)

It carried out similarly to Example 1, and obtained the emulsion (1).

Next, after adding 0.29 g of a 1% by mass sodium sulfate aqueous solution to the obtained emulsion (1), 0.1 N hydrochloric acid aqueous solution was added to adjust the pH to 3.8 to obtain an emulsion (4′). After that, the emulsion (4 ') was transferred to a separate flask equipped with stirring blades, and the liquid temperature was kept at 30° C. while stirring at 200 rpm for 24 hours to obtain silica capsules (the silica capsules had a core composed of model perfume A and consisted of Aqueous dispersion (IV) of a shell composed of silica). The median particle size _D50 of the silica capsules was 2.2 μm.

Example 5

(Process I)

In the same manner as in Example 1, 100.16 g of a silica capsule-containing aqueous dispersion (I) was obtained.

(Process II)

Next, after adding 0.40 g of TEOS to 13.00 g of the aqueous dispersion (I) in 10 seconds, the liquid temperature was kept at 30° C. while stirring for 24 hours, and cooled to room temperature. The second shell of the silica capsules was oxidized to obtain an aqueous dispersion (V) containing silica capsules (in which the model fragrance A was encapsulated by amorphous silica). The silica capsules had a median particle diameter D ₅₀ of 2.1 μm.

Example 6

(Process I)

In the same manner as in Example 4, 100.29 g of a silica capsule-containing aqueous dispersion (IV) was obtained.

(Process II)

Next, 0.39 g of TEOS was additionally added to 13.00 g of the aqueous dispersion (IV) in 10 seconds, stirred for 24 hours while maintaining the liquid temperature at 30° C., and cooled to room temperature. The second shell of the silica capsules was oxidized to obtain an aqueous dispersion (VI) containing silica capsules (in which the model fragrance A was encapsulated by amorphous silica). The silica capsules had a median particle diameter D ₅₀ of 2.2 μm.

Comparative example 1

(Process I')

It carried out similarly to Example 1, and obtained the emulsion (1).

Next, 0.1N hydrochloric acid aqueous solution was added to the obtained emulsion (1) to obtain an emulsion (C1') whose pH was adjusted to 3.8, and this emulsion (C1') was transferred to a separate flask equipped with a stirring blade. , keep the liquid temperature at 30°C while stirring at 200rpm for 24 hours to obtain an aqueous dispersion containing silica capsules (the silica capsules have a core made of model fragrance A and a shell made of silica) ( CI). The median particle size _D50 of the silica capsules is 2.1 μm.

Comparative example 2

(Process I')

It carried out similarly to Example 1, and obtained the emulsion (1).

Next, after adding 1% by mass nitric acid aqueous solution to the obtained emulsion (1) to obtain an emulsion (C2') whose pH was adjusted to 3.8, the emulsion (C2') was transferred to a separate flask equipped with a stirring blade. , the liquid temperature was kept at 30°C while stirring at 200rpm for 24 hours to obtain an aqueous dispersion containing silica capsules (the silica capsules had a core composed of model flavor A and a shell composed of silica) (CII). The median particle size _D50 of the silica capsules is 2.2 μm.

Comparative example 3

(Process I')

It carried out similarly to Example 1, and obtained the emulsion (1).

Next, after adding 10% by mass aqueous citric acid solution to the obtained emulsion (1) to obtain an emulsion (C3') whose pH was adjusted to 3.8, the emulsion (C3') was transferred to a separation tank equipped with a stirring blade. In the flask, the liquid temperature was kept at 30° C. while stirring at 200 rpm for 24 hours to obtain a water dispersion containing silica capsules (the silica capsules had a core composed of model fragrance A and a shell composed of silica). Body (CIII). The median particle size _D50 of the silica capsules is 2.1 μm.

[Evaluation of silica capsules]

[Evaluation of Inclusion Rate of Fragrance Components]

30 mg of the aqueous dispersions containing silica capsules obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were sucked with a dropper, diluted with 50 g of ion-exchanged water, and passed through a membrane filter (manufactured by Millipore Co., Ltd., product name "Omnipore", model number "JAWP04700"), whereby silica capsules were recovered on the membrane filter.

Further, on the membrane filter, the silica capsules were washed with 10 mL of ion-exchanged water, and then 10 mL of hexane was used to wash the silica capsules, and thereafter, the silica capsules were immersed in an internal standard containing Dodecane-containing acetonitrile 10 mL was irradiated with ultrasonic waves for 60 minutes using an ultrasonic irradiation device (manufactured by Branson, model "5510") at an output of 180 W and an oscillation frequency of 42 kHz to elute the fragrance in the silica capsules. After this solution was passed through a membrane filter (manufactured by Toyo Filter Paper Co., Ltd., product name "DISMIC", model number "13JP020AN"), each fragrance component contained in this solution was measured by gas chromatography, and it was set to be contained in two The amount α of each fragrance component of the silica capsule. Next, the inclusion rate of the fragrance component was calculated from the following formula. The results are shown in Table 2 below.

Encapsulation rate of flavor components (%)={(amount of each flavor component contained in silica capsule α)/(amount of each flavor component contained in 30 mg of silica capsule aqueous dispersion β)}×100

It should be noted that the amount β of the fragrance component in the above formula was calculated based on the composition of the model fragrance used and the content in the aqueous dispersion containing silica capsules.

It can be seen from Table 2 that the silica capsules obtained in Examples have a higher inclusion ratio of fragrance components than in Comparative Examples. In addition, it was found that the silica capsules obtained in Examples maintained a high inclusion rate and could be stably included in spite of being subjected to suction filtration when evaluating the inclusion rate.

[industrial availability]

According to the present invention, it is possible to obtain silica capsules in which active ingredients such as fragrances, that is, organic compounds are stably contained at a high inclusion rate, so the silica capsules and the aqueous dispersion containing silica capsules can be favorably applied to the preparation of fragrances. Various products with active ingredients.

Claims (10)

1. A method for producing silicon dioxide microcapsules, wherein, The silica microcapsules have: a shell containing silica as a constituent; and a core containing one or more organic compounds inside the shell, The method for producing silica microcapsules includes the following steps: in the presence of one or more sulfur-containing ions selected from sulfate ions, sulfite ions, and sulfonate ions, supplying the emulsion to the sol-gel reaction to form silica microcapsules, The emulsion is obtained by emulsifying a water phase component containing a cationic surfactant and an oil phase component containing one or more organic compounds and a silica source. 2. the manufacture method of silica microcapsules according to claim 1, wherein, In the step of forming silica microcapsules, one or more compounds (A) selected from sulfuric acid, sulfurous acid, sulfonic acid compounds, and salts thereof are added to the emulsion, and then supplied to Sol-gel reaction. 3. the manufacture method of silica microcapsules according to claim 2, wherein, The compound (A) is at least one selected from sulfuric acid, sulfurous acid, sulfonic acid compounds, and inorganic salts thereof. 4. The method for producing silica microcapsules according to any one of claims 1 to 3, wherein, The amount of the silica source is not less than 10% by mass and not more than 100% by mass relative to the amount of the organic compound. 5. The method for producing silica microcapsules according to any one of claims 1 to 4, wherein, The cationic surfactant is an alkyltrimethylammonium salt having an alkyl group having 10 to 22 carbon atoms. 6. The method for producing silica microcapsules according to any one of claims 1 to 5, wherein, The median diameter _D50 of the emulsified droplets of the emulsion is not less than 0.1 μm and not more than 10 μm. 7. The method for producing silica microcapsules according to any one of claims 1 to 6, wherein, The initial pH of the sol-gel reaction is not less than 3.0 and not more than 4.5. 8. The method for producing silica microcapsules according to any one of claims 1 to 7, wherein, The organic compound is one or more selected from fragrances, fragrance precursors, humectants, antioxidants, antibacterial agents, fertilizers, surface modifiers, and solvents. 9. The method for producing silica microcapsules according to any one of claims 1 to 8, wherein, The silica source contains tetraalkoxysilane as a main component. 10. An aqueous dispersion wherein, Contains silica microcapsules, The silica microcapsules have: a shell containing silica as a constituent; and a core containing one or more organic compounds inside the shell, The total content of sulfate ions, sulfite ions, and sulfonate ions in the aqueous dispersion is not less than 10 ppm and not more than 500 ppm.